package ljl.alg.wangzheng_camp.round1.recursive;

public class _10_1_fib {
    
    public int fib(int n) {
        int a = 0, b = 1;
        while (n-- > 0) {
            int t = a;
            a = b;
            b = (t + b) % 1000000007;
        }
        return a;
    }
}
